This dataset contains information on the Bullseye Snakehead fish found only in southeastern Florida. It is a subset of a larger database, the Nonindigenous Aquatic Species Database (NAS). This information resource is an established central repository for spatially referenced biogeographic accounts of introduced aquatic species. The NAS website provides scientific reports, online/real-time queries, spatial data sets, distribution maps, fact sheets, and general information.

This dataset contains information on all snakehead fishes found in the United States. It is a subset of a larger database, the Nonindigenous Aquatic Species Database (NAS). This information resource is an established central repository for spatially referenced biogeographic accounts of introduced aquatic species. The NAS website provides scientific reports, online/real-time queries, spatial data sets, distribution maps, fact sheets, and general information.

This dataset contains information on all snakehead fishes found in the United States. It is a subset of a larger database, the Nonindigenous Aquatic Species Database (NAS). This information resource is an established central repository for spatially referenced biogeographic accounts of introduced aquatic species. The NAS website provides scientific reports, online/real-time queries, spatial data sets, distribution maps, fact sheets, and general information.

Bullseye snakehead, Channa marulius, was first detected in 2000 in the southern Florida town of Tamarac and has been expanding its geographic range. Environmental DNA (eDNA) analysis is a newly-developed technique used to non-invasively detect cryptic or low-density species, or those that are logistically difficult to study. Genetic material shed into the environment through tissue and body fluids is concentrated from water samples and analyzed for the presence of target species eDNA. To help delineate bullseye snakehead’s geographic range, we developed and validated a species-specific eDNA assay for both quantitative and droplet digital PCR (ddPCR). We then used ddPCR to assess 16 locations in southeast Florida using 222 water samples collected from 2015-2018. Positive eDNA detections were obtained at all six locations that were within the known geographic range of bullseye snakehead. Furthermore, eDNA was detected in six of 10 locations that were previously thought to be outside the periphery of the range but hydrologically connected through the extensive canal system. Over the four years of sampling, estimated occurrence rates (ψ) remained stable and relatively high (ψ = 0.67 [95% Confidence Interval (CI) 0.33-0.95]) near Tamarac, FL, as compared to the most southern sampling sites (ψ = 0.0-0.37). Bullseye snakehead eDNA estimated occurrence rates in the middle region increased between 2016 (0.28 [95% CI 0.03-0.94]) and 2017 (0.66 [95% CI 0.24-0.98]), potentially reflecting eDNA detections related to a growing or expanding population. Bullseye snakehead eDNA was detected at low concentrations on the northern and eastern borders of Everglades National Park, which is an important conservation area and UNESCO World Heritage Site. Despite extensive sampling via electrofishing, no bullseye snakeheads were visually detected in several locations that yielded positive eDNA samples. It is unclear whether eDNA was transported through flowing water or another vector. To date, collection records for this species are confined to urban canals; however, bullseye snakehead may use the interconnected system of canals to disperse to natural conservation areas, such as Everglades National Park, Big Cypress National Preserve and Water Conservation Areas, where it may impact native species via predation and competition.

Data described herein was collected by USGS personnel and the project funded by USGS. Northern snakehead specimens were collected from the Potomac River and its tributaries by regional natural resource management agencies in the course of their field investigations working with this priority invasive aquatic species. Specimens were provided to USGS for the purpose of conducting health related assessments of northern snakehead in the region, with approximately 90 specimens evaluated grossly and histologically for the presence of lesions and abnormalities. Data presented here was collected seasonally (spring through fall) in 2006 and from 2015 to 2017. Data for each specimen includes date and location of collection, morphometrics, gender (if known), and gross abnormalities, and histological lesions observed. This body of data is stored in spreadsheet format.

Data described herein was collected by USGS personnel and the project funded by USGS. Northern snakehead specimens were collected from the Potomac River and its tributaries by regional natural resource management agencies in the course of their field investigations working with this priority invasive aquatic species. Specimens were provided to USGS for the purpose of conducting health related assessments of northern snakehead in the region, with approximately 90 specimens evaluated grossly and histologically for the presence of lesions and abnormalities. Data presented here was collected seasonally (spring through fall) in 2006 and from 2015 to 2017. Data for each specimen includes date and location of collection, morphometrics, gender (if known), and gross abnormalities, and histological lesions observed. This body of data is stored in spreadsheet format.

We analyzed morphological and molecular data from one existing and one newly discovered population of 'bullseye' snakehead (Teleostei: Channidae) from Florida. Morphological and meristic data were collected from museum collections and compared with data from recent taxonomic revisions of related species in the 'Marulius' species group from southeast Asia. Additionally, we performed DNA sequencing of COI barcodes from museum tissue vouchers (corresponding with lots examined for morphology) and compared these sequences with an existing COI barcode library for the 'Marulius' group. These analyses were used to determine the taxonomic identity of snakeheads established in Florida.

We analyzed morphological and molecular data from one existing and one newly discovered population of 'bullseye' snakehead (Teleostei: Channidae) from Florida. Morphological and meristic data were collected from museum collections and compared with data from recent taxonomic revisions of related species in the 'Marulius' species group from southeast Asia. Additionally, we performed DNA sequencing of COI barcodes from museum tissue vouchers (corresponding with lots examined for morphology) and compared these sequences with an existing COI barcode library for the 'Marulius' group. These analyses were used to determine the taxonomic identity of snakeheads established in Florida.

Vector datasets of CWHR range maps are one component of California Wildlife Habitat Relationships (CWHR), a comprehensive information system and predictive model for Californias wildlife. The CWHR System was developed to support habitat conservation and management, land use planning, impact assessment, education, and research involving terrestrial vertebrates in California. CWHR contains information on life history, management status, geographic distribution, and habitat relationships for wildlife species known to occur regularly in California. Range maps represent the maximum, current geographic extent of each species within California. They were originally delineated at a scale of 1:5,000,000 by species-level experts and have gradually been revised at a scale of 1:1,000,000. For more information about CWHR, visit the CWHR webpage (https://www.wildlife.ca.gov/Data/CWHR). The webpage provides links to download CWHR data and user documents such as a look up table of available range maps including species code, species name, and range map revision history; a full set of CWHR GIS data; .pdf files of each range map or species life history accounts; and a User Guide.

The three datasets were used in a model estimating the current and future persistence of 222 populations of southern hognose snakes, as estimated as part of the USFWS Species Status Assessment. Because these datasets contain information about sensitive species at risk of overcollection and harassment, they do not contain any spatial identifying information. The "HESIM_locs" dataset contains a list of southern hognose snake occurrence records with associated year of observation and population ID. The "SEsnakes_locs" dataset contains a list of non-target snake species occurrence records with associated year of observation and population ID. The "HESIM_pops_all" dataset contains a list of southern hognose snake populations with associated habitat metrics of current and future conditions derived from publically available spatial datasets, a habitat suitability model by Crawford et al. 2019, and estimated persistence probability from the analysis. A full description of the methodology and results of the southern hognose snake status assessment is available in the publication: Crawford, B.A., Olds, M.J., Maerz, J.C., and Moore, C.T., 2019. Estimating population persistence for at-risk species using citizen science data. Biological Conservation. In review. The full Species Status Assessment: U.S. Fish and Wildlife Service, 2019. Species status assessment for the southern hognose snake (Heterodon simus). Version 1.1, April 2019. Atlanta, GA. Available at https://ecos.fws.gov/ServCat/DownloadFile/168148.